a. Field of the Invention
The present invention relates to irrigated catheter assemblies. The present invention further relates to ablation electrodes and assemblies, including electrodes in which a proximal direction irrigation fluid flow is generated around the ablation electrode.
b. Background Art
Electrophysiology catheters are used for an ever-growing number of procedures. For example, catheters are used for diagnostic, therapeutic, and ablative procedures, to name just a few examples. Typically, a catheter is manipulated through the patient's vasculature and to the intended site, for example, a site within the patient's heart. The catheter typically carries one or more electrodes, which may be used for ablation, diagnosis, or other treatments.
There are a number of methods used for ablation of desired areas, including for example, radiofrequency (RF) ablation. RF ablation is accomplished by transmission of radiofrequency energy to a desired target area through an electrode assembly to ablate tissue at the target site. Because RF ablation may generate significant heat, which if not controlled can result in excessive tissue damage, such as steam pop, tissue charring, and the like, it is desirable to include a mechanism to irrigate the target area and the device with biocompatible fluids, such as saline solution. The use of saline irrigated ablation catheters can also prevent the formation of soft thrombus and/or blood coagulation.
Typically, there are two classes of irrigated electrode catheters, open and closed irrigation catheters. Closed ablation catheters usually circulate a cooling fluid within the inner cavity of the ablation electrode. Open ablation catheters typically deliver the cooling fluid through open outlets or openings on the surface of the electrode. Open ablation catheters use the inner cavity of the electrode, or distal member, as a manifold to distribute saline solution, or other irrigation fluids known to those skilled in the art, to one or more passageways that lead to openings/outlets provided on the surface of the electrode. The saline thus flows directly through the outlets of the passageways onto the distal electrode member. This direct flow through the distal electrode tip lowers the temperature of the distal tip during operation, often making accurate monitoring and control of the ablative process more difficult.
In general, open irrigated ablation catheters may improve the safety of radiofrequency catheter ablation by preventing protein aggregation and blood coagulation. A particular area of the electrode/catheter where the formation of coagulum or thrombus may occur during ablation procedures is at the proximal end of the electrode.